FiveM server optimization: why it stutters and how to find the cause in an hour

"The server is lagging" is the most common complaint on every FiveM server and the least precise. Behind that sentence are three different things: the server computes too slowly, the player's client draws too slowly, or the connection in between stalls. Each has a different cause and a different tool. If you keep the three apart you find the cause in an hour. If you delete scripts at random you search for weeks.

The three kinds of lag

Server tick: when everyone suffers at once

The FiveM server works in ticks, similar to frames per second. If a tick takes too long because a script computes too much inside it, all players wait. The first look goes to the performance graph in txAdmin: if it shows spikes that coincide with player count or time of day, the server is the problem. Then in the server console:

resmon 1        # Tabelle: ms je Resource, live
profiler record 500
profiler save profil.json   # danach im Browser unter chrome://tracing öffnen

resmon shows per resource how many milliseconds it costs per tick. A healthy server sits below 2 ms in total when idle. A single resource above 0.5 ms idle is suspicious, above 2 ms a bug. The profiler shows which function in that resource eats the time. Typical: a loop that walks all players every tick, a database query that runs on every event, or a script counting all vehicles every second.

Client FPS: when individuals suffer

If it stutters only for some players or only in certain places, the client is overloaded. Press F8 in game and type resmon 1: the same table, now for client scripts. A client script above 0.1 ms idle is already a lot, above 1 ms a bug. Most common reason: a loop with Citizen.Wait(0) checking every frame whether the player is near a point, instead of once per second.

If it is not scripts, it is content. A car park full of vehicles without detail levels, an MLO with 4K textures on every wall, a clothing pack with 200,000 polygons per jacket: all of that costs FPS exactly where it stands. The test is simple: go to the place where it stutters and look at what is different there compared to elsewhere.

Network and OneSync

Rubber banding and vehicles that snap back are almost always network. First rule out the player's line: the client shows ping and packet loss in its settings. If it affects many, the server sends too much data. OneSync Infinity, the default of modern servers, sends each player only what is near them. Scripts that send every player the state of all vehicles every second undermine that. Instead of broadcasting events to everyone, such data belongs in state bags, which GTA itself distributes only to those who need them.

The ten causes that are almost always behind it

1. Loops without a pause: Citizen.Wait(0) in a script that only needs to check something every few seconds.
2. Database queries in events that fire often: a query on every inventory click, 600 queries a minute at 60 players.
3. Vehicles without detail levels. Ten of them in a car park halve the FPS of everyone driving past.
4. Too many entities. Every spawned object, every ped, every parked vehicle stays until somebody removes it. Orphaned vehicles are the classic.
5. 4K textures on clothing and walls where nobody could tell 1K apart.
6. Events to everyone instead of those affected: TriggerClientEvent(-1, ...) for things only two players see.
7. Scripts nobody uses that still run every tick. Every script players do not need daily goes out.
8. Outdated artifacts. Every FiveM version brings performance improvements; a year without updating wastes them.
9. The database on a hard disk instead of SSD, or without indexes on columns being searched (character ID, plate).
10. The host. A server sharing one CPU core with ten others cannot be saved. FiveM needs one fast core, not many.

The procedure in one hour

1. Look at the txAdmin graph: server or client? If tick time is calm, it is not the server.
2. resmon on the affected side. Note the three most expensive resources.
3. Stop the most expensive resource, wait ten minutes, compare the graph. Only then the next one.
4. If it is not a resource: count entities. More than a few hundred vehicles on the map are a problem no matter how good the scripts are.
5. If it is a place: inspect the content there, MLO, vehicles, clothing of the players present.

How 5MCustoms modules are built

Every module is signed off with resmon before it reaches the shop: idle below 0.05 ms in the client, no loop without a pause, database access batched instead of per event. States like duty, restraints or vehicle keys live in state bags, not in events to everyone. Vehicles from the shop have all detail levels, clothing 1K or 2K textures. That does not make a server fast by itself, but it takes the most common causes out of the game.

Justin Beil

Founder of 5MCustoms

Justin has been building FiveM servers, vehicles and scripts for years. 5MCustoms is the framework that grew out of it. What you read here comes from practice, not from a product sheet.

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